2.43. Energy Level http://www.ck12.org
2.43 Energy Level
- Describe energy levels.
- Relate energy levels to orbitals.
- Explain the significance of electrons in the outermost energy level of an atom.
Fireworks are a great way to celebrate happy events. Do you know what causes the brilliant, colored lights of
fireworks? The lights are bursts of energy given off by atoms in the fireworks. What do you suppose causes these
bursts of light? The answer has to do with energy levels of atoms.
What Are Energy Levels?
Energy levels(also called electron shells) are fixed distances from the nucleus of an atom where electrons may be
found. Electrons are tiny, negatively charged particles in an atom that move around the positive nucleus at the center.
Energy levels are a little like the steps of a staircase. You can stand on one step or another but not in between the
steps. The same goes for electrons. They can occupy one energy level or another but not the space between energy
levels.
The model in theFigure2.82 shows the first four energy levels of an atom. Electrons in energy level I (also called
energy level K) have the least amount of energy. As you go farther from the nucleus, electrons at higher levels have
more energy, and their energy increases by a fixed, discrete amount. Electrons can jump from a lower to the next
higher energy level if they absorb this amount of energy. Conversely, if electrons jump from a higher to a lower
energy level, they give off energy, often in the form of light. This explains the fireworks pictured above. When the
fireworks explode, electrons gain energy and jump to higher energy levels. When they jump back to their original
energy levels, they release the energy as light. Different atoms have different arrangements of electrons, so they give
off light of different colors. You can see an animation of electrons jumping from one energy level to another at this
URL: http://cas.sdss.org/dr6/en/proj/advanced/spectraltypes/energylevels.asp.